Abstract: This paper made a study on the efficacy of the environmental condition in the occurance and distribution of weed in farmlands, based on the systematic investigation on the weed flora of Taihu agricultural area,Jiangsu province.It was sugge- sted that the occurance amount and distribution of the weeds were not only closely effected by the natural ecological factors in fields, such as water, soil pH, light, temperature, etc,, but also remarkably controlled by the artificial ecological conditions as cultivation regime, faming technique, herbicide application arid other activities of human being.The weed control strategy of integrating the weed quarantine, weed occurance forecast, chemical control, cultivation regime,faralng technique, biologicall control and weed biomass utilization was also discnsaed in accordance with the biological properties of weeds under different coaditions.